me too
I have a A5 with 2 9/16 chamber. Keep it as it is and just buy some ammo. use the gun for special occasions. If it is your only shotgun, use the $200+ and go buy a used 870 or 1100 for everday shooting.
If the chambe is done incorrectly your out a nice old gun. Even if done well, they are not usually as reliable anymore, sort of like replacing an engine in a car, from that point on littles things will start going wrong.
You have someones Miss flyway duck gun there. Treasure it, because when the original owner showed up with it sometime in the 30's he was most likely a target of derision and insults for bringing that "flock destroyer" into a blind. He kept it in fine condition against all of his friends wishes. You should also.